Tumor Imaging in Experimental Animal Models of Breast Carcinoma with Routinely Available 99mTc-Sestamibi

Fiorella Carla Tesán^1*, Mariano Portillo¹,Vanina Medina², Mariel Nuñez¹, María Jimena Salgueiro¹, Marcela Zubillaga^1 
1Radioisotope Laboratory, Physics Department, School of Pharmacy and Biochemistry, University of Buenos Aires, Buenos Aires, Argentina
²National Scientific and Technical Research Council (CONICET), Buenos Aires, Argentina

A B S T R A C T
The arise of dedicated imaging equipment and techniques facilitated the emergence of translational research paradigm. In this sense, the follow up and tracing of biological processes, pathologic or not, as well as the outcomes of therapy strategies in tumor bearing animals is expected to shorten the bridge between laboratory and patient bed. Thus the aim of this work was to evaluate ^99mTc-sestamibi as a tracer to follow up chemical or clinical interventions in xenografted tumors of MDA MB-231 human breast cancer cell line and N-Nitroso-N-methylurea (NMU) induced mammary tumors. Tumor bearing animalsreceived ^99mTc-sestamibi intravenously. Images were acquired with a gamma camera. 10min and 60min acquisitions were performed and regions of interest were created for semiquantitative analysis. ^99mTc-sestamibi tumor uptake for xenograft model (X) is poor at 10min biodistribution (T/NT_10min: 0.5). Delayed acquisition showed a tumor accumulation even lower (T/NT_60min: not possible to calculate). Chemically induced model (C) showed an important accumulation of ^99mTc-sestamibi in the tumors at the 10min (T/NT_10min: 3.2) and 60min (T/NT_60min:1.7) of biodistribution. Histological analysis showed a 60% of necrosis in X model and a 10% of necrosis in C model. ^99mTc-sestamibi proved not to be useful for X model but it is a suitable tumor tracer for C model.
Keywords: ^99mTc-sestamibi, breast cancer, animal models, imaging, MDA-MB-231, N-Nitroso-N-methylurea